Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The annotations already indicate readOnlyHint=true, so the description's reinforcement of read-only behaviour is less critical. The description adds valuable context beyond annotations by explicitly stating that message reading/sending is unsupported, preventing the agent from expecting message content. It does not cover pagination or rate limits, but with annotations and an output schema that gap is minor.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences and front-loads the core purpose before the important limitation. There is no redundant or filler text.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the simple one-parameter schema, existing output schema, and annotations, the description covers the essential purpose and the key functional limitation. It could clarify what 'activities' means in the returned data, but the output schema likely handles that.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The single parameter 'course_ids' is fully documented in the schema, and the description does not add further detail such as array format, maximum length, or ID source. With 100% schema coverage, the baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('List') and resource ('Chat (real-time chat room) activities') and scopes it to one or more courses. It clearly distinguishes the tool from message-reading tools by stating that message reading/sending is unsupported, though it does not explicitly contrast with a named sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides an implied usage context (listing chat activities for courses) and a clear exclusion ('Reading/sending chat messages is not supported'). However, it does not name an alternative tool or state when an agent should prefer this over other listing tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.